The present invention relates to a novel salt of enantiomer A of 7-chloro-4-(2-oxo-1-phenyl-3-pyrrolidinylidene)1,2,3,4-tetrahydro-2-quinoline carboxylic acid or a solvate thereof, to processes for its preparation, to pharmaceutical compositions containing it and to its use in therapy and in particularly its use as medicine for antagonising the effects of excitatory amino acids upon the NMDA receptor complex.
The compound 7-chloro-4-(2-oxo-1-phenyl-3-pyrrolidinylidene)-1,2,3,4-tetrahydro-2-quinolinecarboxylic acid of formula (I) is inter alia described in WO 99/64411 which also refers to physiologically acceptable salts thereof and more particularly it describes an enantiomer of the compound of formula (I), which is referred to therein as enantiomer A and a sodium salt thereof. 
The enantiomer A of 7-chloro-4-(2-oxo-1-phenyl-3-pyrrolidinylidene)-1,2,3,4-tetrahydro-2-quinolinecarboxylic acid is a particularly potent antagonist of the NMDA receptor complex, and for its use in medicine there exists a need for the compound to be prepared in a form suitable for ease of isolation in a large scale manufacture and for ease of formulating into an acceptable product for administration to patients. These requirements are not conveniently met by either enantiomer A or sodium salt thereof.